1. Field of the Invention
The present invention relates to an image forming apparatus having a mode to print without margins and a control method therefore.
2. Description of the Related Art
Image forming apparatuses utilizing the electrophotographic process, such as printers, copiers, fax machines, and the like, form toner images, which are initially produced on photosensitive drums serving as first image carriers, on printing paper, transparencies and other printing materials. In addition, to carry out successive transfer of multicolor toner (developer), color image forming apparatuses perform primary transfer onto a rotary belt-shaped second image carrier and then secondary transfer from the second image carrier onto a printing material.
If the toner image is smaller than the size of the printing material, namely, during printing with margins, in which a margin is formed in the edge portion of the printing material, all of the toner in the toner image formed on the second image carrier comes into contact with the printing material during transfer onto the printing material. For this reason, toner of toner image formed on the second image carrier does not adhere to the rotary belt and transfer roller arranged opposite the transfer unit. However, in printing without margins, in which an image is formed over the entire printing material such that no margin is generated in the edge portion of the printing material, the image forming apparatus forms a toner image that is larger than the printing material area such that no margin is formed even if the position of the printing material is slightly shifted relative to the standard position. For this reason, toner used for imaging exceeding the printing material area may adhere to the transfer roller and rotary belt during transfer onto the printing material. Additionally, there is the risk that toner adhered to the transfer roller and rotary belt may be re-transferred to the back surface of the printing material and may cause contamination of back surface. In addition, toner used for imaging exceeding the printing material area does not get transferred onto the printing material and remains as waste toner on the second image carrier. For this reason, it is believed that currently used image forming apparatuses require technology either for removal of such waste toner etc. or for decreasing the amount of waste toner.
JP 2003-316224A (hereinafter, referred to as “Patent document 1”) describes a technology which, at a low cost, enables users to accurately ascertain the amount of accumulated waste toner by continuously issuing reminders of changes in the amount of accumulated waste toner.
JP H11-268363A (hereinafter referred to as “Patent document 2”) describes a technology, in which material to be printed is adhered to a sheet larger than the material to be printed and an image is formed that is larger than the size of the material to be printed and smaller than the sheet and, after printing, the material is peeled off the sheet. This prevents waste toner from remaining on the second image carrier (intermediate transfer member).
JP 2000-280563A (hereinafter referred to as “Patent document 3”) discloses a technology, in which dedicated sheets for printing without margins are used and the peripheral edge portions of the sheets are trimmed after printing. This prevents waste toner from remaining on the second image carrier.
However, in the image forming apparatus of Patent document 1, when the amount of toner in the waste toner container located in the second image carrier reaches a “container full” point, the image forming apparatus has to be stopped, and either a new waste toner container has to be used, or the remaining waste toner has to be discarded. Furthermore, despite the fact that such burdensome operations are required in the image forming apparatus of Patent document 1, there is the risk that the waste toner container may reach a “container full” point. If a “container full” point is reached, the image forming apparatus will stop printing. In addition, in the image forming apparatuses of Patent document 2 and Patent document 3, the user has to trim the sheets or perform other operation after printing, which is extremely burdensome. Furthermore, it is necessary to have dedicated printing material for printing without margins on hand. For this reason, ordinary paper cannot be utilized, printing costs increase, and, in addition, there is the risk that the types of the sheets used may be limited.